A few days after I published Hackage revisions in Nix I got a comment from Wolfgang W that the next release of Nix will have a callHackageDirect with support for specifying revisions. The code in PR #284490 makes callHackageDirect accept a rev argument. Like this: haskellPackages.callHackageDirect { pkg = "openapi3"; ver = "3.2.3"; sha256 = "sha256-0F16o3oqOB5ri6KBdPFEFHB4dv1z+Pw6E5f1rwkqwi8="; rev = { revision = "4"; sha256 = "sha256-a5C58iYrL7eAEHCzinICiJpbNTGwiOFFAYik28et7fI="; }; } { } That's a lot better than using overrideCabal! Tags: haskell nix ..read more

Posted on 2024-04-18 by Oleg Grenrus Recently I came up with a criteria for a good warning to have in a compiler: If compiler makes a choice, or has to deal with some complication, it may well tell about that. That made me think about warnings I implemented into GHC over the years. They are fine. Let us first understand the criteria better. It is better explained by an example which triggers few warnings: foo :: Char foo = let x = 'x' in let x = 'y' in x First warning is -Wname-shadowing: Shadow.hs:3:11: warning: [-Wname-shadowing] This binding for ‘x’ shadows the existing bindi ..read more

Last year, at the end of winter, we wrote our impressions of the trends and evolution of infrastructure and configuration management after attending FOSDEM and CfgMgmtCamp. We’re at it again, but with Kubecon this year, the biggest cloud native computing conference. If you’ve never heard of cloud native computing before, it has a number of definitions online, but the simplest one is that it’s mostly about Kubernetes. Kubecon is a huge event with thousands of attendees. The conference spanned several levels of the main convention center in Paris, with a myriad of conference rooms and a whole fl ..read more

I thought about this because of yesterday's article about the person who needed to count the 3-colorings of an icosahedron, but didn't try constructing any to see what they were like. Around 2015 Katara, then age 11, saw me writing up my long series of articles about the Cosmic Call message and asked me to explain what the mysterious symbols meant. (It's intended to be a message that space aliens can figure out even though they haven't met us.) I said “I bet you could figure it out if you tried.” She didn't believe me and she didn't want to try. It seemed insurmountable. “Okay,” I said, handi ..read more

GHC 9.6.5 is now available Zubin Duggal - 2024-04-16 The GHC developers are happy to announce the availability of GHC 9.6.5. Binary distributions, source distributions, and documentation are available on the release page. This release is primarily a bugfix release addressing some issues found in the 9.6 series. These include: Bumping the bundled process library to 1.6.19.0 to avoid a potential command injection vulnerability on Windows for clients of this library. This isn’t known to affect GHC itself, but allows users who depend on the installed version of the process to avoid the issue. F ..read more

GHC 9.10.1-alpha3 is now available bgamari - 2024-04-15 The GHC developers are very pleased to announce the availability of the third alpha release of GHC 9.10.1. Binary distributions, source distributions, and documentation are available at downloads.haskell.org. We hope to have this release available via ghcup shortly. GHC 9.10 will bring a number of new features and improvements, including: The introduction of the GHC2024 language edition, building upon GHC2021 with the addition of a number of widely-used extensions. Partial implementation of the GHC Proposal #281, allowing visible quan ..read more

I will be presenting a summary of the content in this post live on an upcoming episode of The Haskell Unfolder (scheduled for April 16th, 2024, 1830 UTC). I encourage you to join the live stream and submit any questions you might have after reading this post! The Haskell Unfolder Episode 23: specialisation Overloaded functions are common in Haskell, but they come with a cost. Thankfully, the GHC specialiser is extremely good at removing that cost. We can therefore write high-level, polymorphic programs and be confident that GHC will compile them into very efficient, monomorphised code. In th ..read more

I recently wrote about things that are backwards in Australia. I made this controversial claim: The sun in the Southern Hemisphere moves counterclockwise across the sky over the course of the day, rather than clockwise. Instead of coming up on the left and going down on the right, as it does in the Northern Hemisphere, it comes up on the right and goes down on the left. Many people found this confusing and I'm not sure our minds met on this. I am going to try to explain and see if I can clear up the puzzles. “Which way are you facing?” was a frequent question. “If you're facing north, it com ..read more

I don't know that I have a point about this, other than that it makes me sad. A recent Math SE post (since deleted) asked: How many different ways are there to color the vertices of the icosahedron with 3 colors such that no two adjacent vertices have the same color? I would love to know what was going on here. Is this homework? Just someone idly wondering? Because the interesting thing about this question is (assuming that the person knows what an icosahedron is, etc.) it should be solvable in sixty seconds by anyone who makes the least effort. If you don't already see it, you should try. T ..read more

Posted on 2024-04-12 by Oleg Grenrus inspection-testing was created over five years ago. You may want to glance over Joachim Breitner A promise checked is a promise kept: inspection testing) Haskell Symposium paper introducing it. Already in 2018 I thought it's a fine tool, but it's more geared towards /library/ writers. They can check on (some) examples that the promises they make about the libraries they write work at least on some examples. What we cannot do with current inspection-testing is check that the actual "real-life" use of the library works as intended. Luckily, relatively recentl ..read more